When Eric Schmidt joined Google as CEO in 2001, the theory was that the company’s founders, Larry Page and Sergey Brin, needed a seasoned tech executive to help them run the burgeoning business they had created. When he gave up that position to Page almost a decade later, he famously tweeted “day-to-day adult supervision no longer needed!”

But Schmidt stayed on as executive chairman and assumed the same position at Alphabet when Google reorganized itself to give its far-flung efforts more independence. And even though Alphabet is very much Page’s company, Schmidt has played a key role as a public face of the company and an emissary to Washington, DC; the EU; and other entities—a particularly valuable role given that Page is less interested in being a highly visible public figure than any other major tech CEO.

Now Schmidt is stepping down as executive chairman. The fact it’s happening is less startling than that he stayed almost seven years in the position—which, according to a 2011 New Yorkerpiece by Ken Auletta, he originally envisioned holding for only a year. (Schmidt will remain a technical adviser and Alphabet board member.)

When Schmidt makes news, it’s often for saying odd and unnerving things such as that Google’s approach to its users’ privacy is to brush up against the “creepy line.” But his real legacy is not that or his current elder-statesman status. It’s that he was Google CEO when the company figured out how to make search advertising into one of the most profitable business models in history. He was also there when the company branched into news and email and operating systems and myriad other enterprises, not always successfully but usually in surprising, ambitious ways that buttressed its core advertising business.

Though today’s Alphabet may reflect Page and Brin’s vision more than Schmidt’s, they’d never have been in a position to pursue it without the adult supervision which Schmidt provided during a crucial era.